Magnetic recording media are widely used in audio tapes, video tapes, computer tapes, disks and the like. Magnetic media may use thin, metal layers as the recording layers or may comprise particulate magnetic compounds as the recording layer. The latter type of recording media employs particulate material such as ferromagnetic iron oxides, chromium oxides, ferromagnetic alloy powders and the like dispersed in binders and coated on the substrate. In general terms, magnetic recording media generally comprises a magnetic side coated onto at least one surface of a non-magnetic substrate (e.g., a film for a magnetic recording tape applications). In certain designs, the magnetic side is formed of a single layer directly onto the non-magnetic substrate. In an alternative approach, a dual layer magnetic side construction is employed, including a lower support layer coated onto the substrate and a thin magnetic recording layer coated onto the lower support layer. The two layers may be formed simultaneously or sequentially. The support layer is typically non-magnetic and generally comprised of a non-magnetic powder dispersed in the binder. Conversely, the magnetic recording layer comprises one or more metal particle powders or pigments dispersed in the binder system.
Magnetic tapes may also have a backside coating applied to the opposing side of the non-magnetic substrate in order to improve the durability, electroconductivity, and tracking characteristics of the magnetic recording media. The backside coatings are typically combined with a suitable solvent to create homogenous mixture which is then coated onto the substrate. The coated substrate is dried, calendered if desired, and cured. The formulation for the backside coating also comprises pigments in a binder system.
Typical backsides include carbon black or other material having particle sizes configured to form a smooth background with some larger particles dispersed therein to generally improve durability and frictional characteristics of the backside during manufacturing and use. For example, FIG. 1 illustrates a portion of a prior art magnetic recording medium 10 in the form of a wound, magnetic recording tape. When the magnetic recording tape is wound, a single length of the magnetic recording tape is wrapped to define a first winding 12 and a second winding 14 circumferentially extending around the first winding 12, where a portion of each winding 12 and 14 is illustrated in FIG. 1. Other windings of the magnetic storage tape 10 extend circumferentially around the second winding 14 and/or extend below the first winding 12. Each winding 12 and 14 defines a recording or front surface 16 and a backside or back surface 18 opposite the recording surface 16. As illustrated, the features of backside surface 18 are greatly exaggerated for illustrative purposes. When wound, the backside surface 18 of the second winding 14 interfaces with the recording surface 16 of the first winding 12.
Typical magnetic recording mediums include backside surfaces 18 having bimodal roughness defined by a relatively smooth general characteristic with a plurality of relatively large particles dispersed thereon to decrease friction and increase durability. The bimodal roughness of the backside surface 18 defines a plurality of peaks 20 and valleys 22. Since the second winding 14 extends on top of or around the first winding 12, when wound, the peaks 20 of the second winding 14 contact the front surface 16 of the first winding 12 and the valleys 22 and other areas of the backside surface 18 may not actually contact the first winding 12.
With this in mind, the contact area between adjacent windings 12 and 14 is limited, which serves to decrease friction between windings 12 and 14 as well as between the magnetic recording tape 10 and read/write mechanisms during use. In some instances, the interaction between the peaks 20 of the second winding 14 and the front surface 16 of the first winding 12 causes the peaks 20 to be imprinted or otherwise transmitted to the front surface 16 of the first winding 12. The imprints, pits, or embossments defined in the front surface 16 can damage the recording characteristics of the magnetic recording tape 10. With the above in mind, it is desirable to create a magnetic recording medium having a backside configured to improve the durability and frictional characteristics of the magnetic recording medium while decreasing embossment of the recording surfaces of the magnetic recording medium.